A couple of months ago, I purchased Lego Mindstorms EV3 31313. I am very satisfied, it exceeded my expectations. It lets you build and program robots without bothering you with time consuming electrical/electronic details.
When programming it, I noticed that some things that would be very easy with languages like Java or C# take longer with the EV3 programming environment. As an example, I wanted to record the reflected light intensity from the color sensor for 5 seconds and then display the largest value. Below you can see the screen shot of the program. You can download it from my GitHub lego repo.
Update October 2016: I started teaching robotics to a 13 year old son of a relative. You can see our first video here.